C.S. Lewis (1898-1963), the author of "The Chronicles of Narnia," "Mere Christianity" and "The Screwtape Letters," was far from a perfect human being, and, Christian that he was, would have been the first to admit it.

Nonetheless, in a new biography of the writer and scholar, Alister McGrath quickly piles up good reasons for a reader to like Lewis. The writer disliked denominational squabbling and literary theory; he stood in favor of animals, alcohol and reading old books.

To tip the scales even further, Lewis' friendship and encouragement persuaded J.R.R. Tolkien to finish writing "The Hobbit" and move on to "The Lord of the Rings." That alone would earn Lewis an eternal pint of Barliman's Best.

McGrath is an Anglican priest and a professor of theology at King's College London. While this biography is published by Christian-oriented Tyndale House; it's a thoughtful, nuanced, lucid literary biography that could be read by people of any or no faith. But McGrath's Christian background informs his careful readings of Lewis' works — apologetics, fiction and scholarship.

Born in Belfast, Lewis fell in love with Scandinavian myths and sagas as a teen. His studies in classical literature were interrupted by service in World War I, where he was wounded. He returned to Oxford, earned his degrees, and was elected a fellow and tutor in English at Magdalen College. As a scholar, he specialized in medieval and Renaissance literature.

His talks with Tolkien and other friends, and his readings, slowly brought him from atheism to theism to Christianity to membership in the Church of England. "Lewis's love of literature is not a backdrop to his conversion; it is integral to his discovery of the rational and imaginative appeal of Christianity," McGrath writes.

The biographer spends significant energy re-evaluating the commonly accepted dates of the steppingstones in Lewis' conversion journey. While that's no doubt important to scholars, it was less so to this common reader.

Though a layman, through his writings and radio talks Lewis became Britain's most important public advocate for and explainer of Christianity. But Lewis eventually turned from rationally defending his faith to exploring it imaginatively in stories, notably the Narnia tales, which both McGrath and history, to this point, have judged his most powerful works. While written for children, they draw on Lewis' deep grasp of literature and myth. His "vision of goodness and greatness is not set forth as a logical and reasoned argument, but is affirmed and explored through the telling of a story — a story that captures the imagination."

McGrath also explores the dark and odd threads in Lewis' life, including his broken connection with his father (McGrath sees mistakes on both sides); his unusual long-term relationship with the mother of a fellow soldier who died in World War I; and his surprising late-life marriage to American writer Joy Davidman Gresham.

McGrath quotes her son Douglas, many years later, as saying his mother went to England specifically to seduce Lewis. Lewis' friends saw her as a gold digger.

At first, he enjoyed her sense of humor and intellectual gifts, then she became an important collaborator, even a muse. When she died of cancer a few years after their marriage, he was torn apart and his faith was tested, a time he documented in the gut-wrenching book "A Grief Observed."

Lewis' final years were challenging, marked by illness and financial worries. He died on the day of President John F. Kennedy's assassination.

Lewis, McGrath points out, has always been appreciated more in the United States than in England, even though he never visited here. His popularity in the U.S. is as much religious as it is cultural: "Lewis is trusted and respected by many American Christians, who treat him as their theological and spiritual mentor. Engaging both heart and mind, Lewis opened up the intellectual and imaginative depths of the Christian faith like nobody else."

McGrath also sees Lewis as resonating with many Americans because the writer "represents a lay form of Christianity which has no special place for clergy or ecclesiastical institutions."

McGrath notes that Lewis has his detractors, both from the fundamentalist wing of Christianity and from the secular humanist world, notably Philip Pullman, whose "His Dark Materials" trilogy can be seen as a riposte to the Narnia stories.

For Lewis, whose scholarly works were on late medieval and 16th-century literature, "the only reliable critic of a writer's value is time, and the only reliable measure is the enjoyment that results from reading that writer's works." McGrath's biography, published 50 years after the writer's death, is the latest sign that Lewis' works of imagination will continue to be enjoyed for a long time to come.